Xuan left home at 11.35 a.m. and drove towards the campsite. 2 hours later, her cousin left their home and drove towards the same campsite at 86 km/h. When the cousin reached the campsite at 4.35 p.m., Xuan had another 6 km to travel. What was Xuan’s average speed? Express your answer in mixed number.
Time that the Xuan's cousin started driving = 1.35 p.m.
Duration that Xuan's cousin drove from 1.35 p.m. to 4.35 p.m. = 3 h

Distance that Xuan's cousin travelled
= 3 x 86
= 258 km

Distance that Xuan travelled by the time her cousin reached the city
= 258 - 6
= 252 km

Time that Xuan took to travel 252 km = 5 h

Xuan's average speed
= 252 ÷ 5
= 50²₅ km/h

Answer(s): 50²₅ km/h